. >> we have got even very good at the science of this. it's not perfect, and i think one of the reasons that this is coming out is because it's obvious that it's not perfect, but it's good enough to catch people. lance armstrong has been caught. jenna: a quick follow-up to this, since you were working with this agency since 1999, did you have any indication, i mean did you feel like you had information that was for sure that he was doing this. and just couldn't peg it on him? what was it like inside the agency? well, we really don't get involved in our committee as to the various case ed casess that are being prosecuted. we are more involved with what constitutes a doping offense. a doping offense does not necessarily mean a positive drug terbgs it can be other violations of the process with the same sanctions. jenna: a quick final question to the doctor then i want you to weigh into this as well. based on what you no about the races and what kind of substances might be used, how many people would it take to elude these types of tests. >>